1. Field of the Invention
The present invention relates to image capture lenses and image capture apparatuses. For example, the present is suitably applied to a macro lens which is used for an interchangeable-lens camera and a digital still camera.
2. Description of the Related Art
To date, a macro lens has been a versatile lens capable of close-up shooting at an extremely close position to a subject, and at the same time, capable of shooting at infinity in the same manner as a normal lens. In general, it is desirable for the macro lens to have been subjected to favorable aberration correction both for closest-up focusing and for infinity focusing.
In order to meet this demand, a so-called floating mechanism, in which at least two lens groups are independently moved for focusing, is often employed. Thus, macro lenses which enable a wide range of shooing, for example, from shooting at infinity to life-size shooting, have been provided (for example, Japanese Unexamined Patent Application Publication Nos. 62-195617 and 63-247713). At the same time, a macro lens having a retrofocus front-lens group has also been proposed (for example, Japanese Unexamined Patent Application Publication No. 2005-189727).
Also, in recent years, digital still cameras having an image size of a 35-mm film and using an imaging device, such as a CCD (Charge Coupled Device), etc., which is smaller than that image size, have been used.
In this case, since an imaging device, such as a small CCD, etc., is used in a digital still camera, it is necessary to employ a lens with a short focal length in order to obtain the same angle of view as that of a 35-mm film. However, when a main unit of a camera has the same configuration and size, even if the focal length is shortened, it becomes necessary to have a relatively long back focus in the same manner as before.
However, a macro lens employing a floating mechanism is often based on a so-called Gaussian lens having symmetrical arrangement of lens elements in a front-rear direction. Thus, the focal length is not made short with respect to the back focus.
Also, further miniaturization is demanded for digital still cameras. In a floating method, in which two lens groups or more are to be moved, it is necessary to regulate movement tracks of individual lens groups by cams. Accordingly, the structure thereof becomes complicated, and thus the method is not well suited for miniaturization and weight saving.